Power supply circuit, circuit board and electronic equipment

Abstract

The utility model relates to the field of electronic circuits, and discloses a power supply circuit, a circuit board and electronic equipment. The power supply circuit comprises a silicon controlled rectifier, a zero cross detection circuit, a controller and a driving circuit, the silicon controlled rectifier comprises a gate pole, a first main electrode and a second main electrode, the first main electrode can be electrically connected with a load, and the load and the silicon controlled rectifier can form a mains supply loop. The zero-cross detection circuit can respond to the voltage between the first main electrode and the second main electrode to output a zero-cross detection signal, the controller can output a control signal, and the driving circuit can respond to the zero-cross detection signal output by the zero-cross detection circuit and the control signal output by the controller to drive the silicon controlled rectifier to connect or disconnect a mains supply loop. Therefore, according to the embodiment, the zero-crossing detection signal and the control signal can be synthesized to drive the silicon controlled rectifier to be switched on or switched off, the zero-crossing detection signal does not need to be subjected to interruption processing, and the zero-crossing switching-on or switching-off control reliability of the silicon controlled rectifier can be improved.

Description

Technical Field

[0001] The utility model relates to the field of electronic circuits, and in particular to a power supply circuit, a circuit board and electronic equipment. Background Art

[0002] Silicon controlled rectifier (SCR) is a high-power electrical component, also known as thyristor. In the automatic control system, thyristor can be used as a high-power driver to control high-power equipment with a small-power control. It can be used as a controlled rectifier, a contactless switch or in a circuit to achieve voltage regulation. It is widely used in AC and DC motor speed regulation systems, power regulation systems and follow-up systems.

[0003] In traditional technology, a microcontroller is usually used to detect whether the mains power passes through zero. When the mains power passes through zero, the microcontroller outputs a drive signal through zero-crossing interrupt processing to drive the thyristor to turn on or off. However, when the microcontroller detects whether the mains power passes through zero, it is easily interfered, and the interrupt processing has a certain delay or the risk of being interrupted. Therefore, the reliability of the zero-crossing turn-on or turn-off control of the thyristor is not high, which easily leads to the thyristor not being turned on or off at zero. Utility Model Content

[0004] One purpose of the embodiments of the utility model is to provide a power supply circuit, a circuit board and an electronic device, which can solve the technical problem that the reliability of the thyristor zero-crossing turn-on or turn-off control is low.

[0005] In a first aspect, an embodiment of the utility model provides a power supply circuit, comprising:

[0006] A thyristor, comprising a gate, a first main electrode and a second main electrode, wherein the first main electrode of the thyristor is used to electrically connect to a load, the load and the thyristor can form a mains power supply circuit, the thyristor can turn on or off the mains power supply circuit, and when the mains power supply circuit is formed, the load can be powered;

[0007] a zero-crossing detection circuit, electrically connected to the first main electrode of the thyristor and the second main electrode of the thyristor, respectively, and configured to output a zero-crossing detection signal in response to a voltage between the first main electrode of the thyristor and the second main electrode of the thyristor;

[0008] A controller, used for outputting a control signal;

[0009] The driving circuit is electrically connected to the zero-crossing detection circuit, the controller and the gate of the thyristor respectively, and is used to respond to the zero-crossing detection signal output by the zero-crossing detection circuit and the control signal output by the controller to drive the thyristor to turn on or off the mains power supply circuit.

[0010] In a second aspect, an embodiment of the utility model provides a circuit board, comprising the power supply circuit as described above.

[0011] In a third aspect, an embodiment of the utility model provides an electronic device, including the electronic device as described above.

[0012] In the power supply circuit provided by the embodiment of the utility model, the power supply circuit includes a thyristor, a zero-crossing detection circuit, a controller and a driving circuit, the thyristor includes a gate, a first main electrode and a second main electrode, the first main electrode of the thyristor can be electrically connected to the load, the load and the thyristor can form a mains power supply circuit, the thyristor can turn on or off the mains power supply circuit, and the mains power supply circuit can be formed to supply power to the load, the zero-crossing detection circuit is electrically connected to the first main electrode of the thyristor and the second main electrode of the thyristor respectively, and can respond to the voltage between the first main electrode of the thyristor and the second main electrode of the thyristor to output a zero-crossing detection signal, the controller can output a control signal, the driving circuit is electrically connected to the zero-crossing detection circuit, the controller and the gate of the thyristor respectively, and can respond to the zero-crossing detection signal output by the zero-crossing detection circuit and the control signal output by the controller to drive the thyristor to turn on or off the mains power supply circuit. Therefore, the present embodiment can drive the thyristor to turn on or off by combining the zero-crossing detection signal and the control signal, and the zero-crossing detection signal does not need to be interrupted, which is conducive to improving the reliability of the zero-crossing turn-on or turn-off control of the thyristor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] One or more embodiments are illustrated only as examples in the corresponding drawings, and these examples do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0014] Figure 1 It is a structural schematic diagram of a power supply circuit provided by an embodiment of the utility model;

[0015] Figure 2 It is a structural schematic diagram of a power supply circuit provided by another embodiment of the utility model;

[0016] Figure 3 This is a schematic diagram of the principle of a hysteresis comparator provided by an embodiment of the utility model;

[0017] Figure 4 It is a circuit structure schematic diagram of a power supply circuit provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. In addition, the terms "first", "second", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0019] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0020] The present utility model provides a power supply circuit. Figure 1 The power supply circuit 100 includes a thyristor 10 , a zero-crossing detection circuit 20 , a controller 30 and a driving circuit 40 .

[0021] The thyristor 10 includes a gate G, a first main electrode T1 and a second main electrode T2. The first main electrode T1 of the thyristor 10 can be electrically connected to the load RL. The load RL and the thyristor 10 can form a mains power supply circuit. The thyristor 10 can turn on or off the mains power supply circuit. When the thyristor 10 is in the on state, the load RL and the thyristor 10 form a mains power supply circuit. At this time, the mains can supply power to the load RL through the mains power supply circuit. When the thyristor 10 is in the off state, the thyristor 10 disconnects the mains power supply circuit, and the mains stops supplying power to the load RL.

[0022] In some embodiments, the thyristor 10 is a bidirectional thyristor, which is structurally equivalent to two unidirectional thyristors connected in reverse. This type of thyristor has a bidirectional conduction function, and its on-off state is determined by the voltage applied to the gate. Applying a positive pulse (or negative pulse) to the gate can make it conduct in the forward direction (or reverse direction).

[0023] See also Figure 2 One end of the load RL is electrically connected to the live wire L, the other end of the load RL is electrically connected to the first main electrode T1 of the thyristor 10, and the ground terminal GND is electrically connected to the neutral wire N. When the thyristor 10 is in the on state, the live wire L, the load RL, the thyristor 10 and the neutral wire N can form a loop, that is, the thyristor 10 turns on the AC power supply loop, and the load RL is powered at this time; when the thyristor 10 is in the off state, the live wire L, the load RL, the thyristor 10 and the neutral wire N fail to form a loop, that is, the thyristor 10 turns off the AC power supply loop, and the load RL is not powered at this time.

[0024] The load RL can be any type of electrical appliance, such as a motor, a heater, etc.

[0025] The zero-crossing detection circuit 20 is electrically connected to the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 , respectively, and can output a zero-crossing detection signal in response to the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 .

[0026] As mentioned above, the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 is also the voltage difference between the live line voltage and the neutral line voltage. The zero-crossing detection signal is a signal used to reflect whether the voltage difference between the live line voltage and the neutral line voltage is zero. The moment when the voltage difference between the live line voltage and the neutral line voltage is zero is the zero point.

[0027] Take the example of 220V / 50Hz AC output from the live wire and the neutral wire. The AC power is a sinusoidal voltage that continuously changes at a frequency of 50Hz. When the positive half-wave and negative half-wave of the AC power alternate, the voltage difference between the live wire voltage and the neutral wire voltage is exactly zero. This moment is the zero point.

[0028] When using AC to supply power to high-power loads, thyristors are usually used as contactless switches to control the power supply of high-power loads. Since the di / dt and dv / dt generated by the thyristor when it is turned on at the zero point are the smallest, it is very helpful for the life of the thyristor and external interference. Therefore, the control circuit that does not control the conduction angle generally hopes that the thyristor can be turned on or off at the zero point. In order to achieve the thyristor turning on or off at the zero point, it is often necessary to perform a zero detection function. Zero detection means that in the AC circuit, when the waveform changes from the positive half cycle to the negative half cycle or from the negative half cycle to the positive half cycle, it passes through the zero point, and the system must detect this zero point. When the system detects the zero point, the thyristor contacts must be turned on or off at or near the zero point.

[0029] In some embodiments, the zero-crossing detection signal includes a first level type signal and a second level type signal, and the first level type signal and the second level type signal are different level type signals, for example, the first level type signal is a high level signal and the second level type signal is a low level signal, or the first level type signal is a low level signal and the second level type signal is a high level signal.

[0030] The controller 30 can output a control signal, which includes a first level type signal and a second level type signal. The first level type signal and the second level type signal are different level type signals. For example, the first level type signal is a high level signal and the second level type signal is a low level signal, or the first level type signal is a low level signal and the second level type signal is a high level signal.

[0031] The control signal is a signal for controlling the conduction or disconnection of the thyristor 10. For example, when the thyristor 10 needs to be controlled to be turned on, the controller 30 may output a high level signal, and when the thyristor 10 needs to be controlled to be turned off, the controller 30 may output a low level signal.

[0032] It is worth noting that, in this embodiment, the on or off control of the thyristor 10 does not completely depend on the control signal.

[0033] In some embodiments, the controller 30 can be any general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA), single chip microcomputer, ARM (Acorn RISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components or any combination of these components. In addition, the controller 30 can also be any conventional processor, controller, microcontroller or state machine. The controller 30 can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP and / or any other such configuration.

[0034] The driving circuit 40 is electrically connected to the zero-crossing detection circuit 20 , the controller 30 and the gate G of the thyristor 10 , respectively, and can respond to the zero-crossing detection signal and the control signal to drive the thyristor 10 to turn on or off the mains power supply circuit.

[0035] For example, when the zero-crossing detection signal is a high-level signal, if the control signal is also a high-level signal, the drive circuit 40 drives the thyristor 10 to turn on the AC power supply circuit; if the control signal is a low-level signal, the drive circuit 40 drives the thyristor 10 to disconnect the AC power supply circuit; when the zero-crossing detection signal is a low-level signal, no matter whether the control signal is a high-level signal or a low-level signal, the drive circuit 40 drives the thyristor 10 to disconnect the AC power supply circuit.

[0036] Therefore, on the one hand, the zero-crossing detection signal output by the zero-crossing detection circuit 20 does not need to be interrupted, and there is no risk of delay or interruption, which is beneficial to improving the reliability of the zero-crossing turn-on or turn-off control of the thyristor 10. On the other hand, the zero-crossing turn-on or turn-off control of the thyristor 10 does not completely rely on the control signal output by the controller 30 or the zero-crossing detection signal output by the zero-crossing detection circuit 20, but is jointly controlled by the control signal and the zero-crossing detection signal, which is beneficial to further improve the reliability of the zero-crossing turn-on or turn-off control of the thyristor 10.

[0037] In some embodiments, see Figure 2 The zero-crossing detection circuit 20 includes a voltage sampling circuit 21 , a reference voltage circuit 22 and a comparison circuit 23 .

[0038] The voltage sampling circuit 21 is electrically connected to the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 , and can sample the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 and output a sampled voltage.

[0039] In some embodiments, Figure 2 As shown, the voltage sampling circuit 21 includes a first voltage dividing circuit 211 and a second voltage dividing circuit 212 .

[0040] The first voltage divider circuit 211 and the second voltage divider circuit 212 can divide the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 , and the divided voltage is the sampling voltage.

[0041] The first voltage divider circuit 211 or the second voltage divider circuit 212 may include one resistor or may include multiple resistors. The multiple resistors may be connected in series or in parallel to form a lumped resistor module.

[0042] In some embodiments, see Figure 4 The first voltage divider circuit 211 includes a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9.

[0043] One end of the seventh resistor R7 is electrically connected to the first main electrode T1 of the thyristor 10 , the other end of the seventh resistor R7 is electrically connected to one end of the eighth resistor R8 , the other end of the eighth resistor R8 is electrically connected to one end of the ninth resistor R9 , and the other end of the ninth resistor R9 is electrically connected to the comparison circuit 23 .

[0044] In some embodiments, Figure 4 As shown, the second voltage divider circuit 212 includes a tenth resistor R10.

[0045] One end of the tenth resistor R10 is electrically connected to the first voltage divider circuit 211 and the comparison circuit 23 , respectively, and the other end of the tenth resistor R10 is grounded.

[0046] Assuming that the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 is Vd, the sampling voltage can be expressed as Vs=Vd*R10 / (R7+R8+R9+R10). It can be seen that the sampling voltage Vs is proportional to the voltage Vd, Vs:Vd=R10:(R7+R8+R9+R10).

[0047] Therefore, by adjusting the resistance values ​​of the seventh resistor R7 , the eighth resistor R8 , the ninth resistor R9 and the tenth resistor R10 , the proportional relationship between the sampling voltage Vs and the voltage Vd can be adjusted.

[0048] The reference voltage circuit 22 can generate a preset reference voltage. Those skilled in the art can determine a suitable preset reference voltage according to actual needs, which is not limited here.

[0049] In some embodiments, Figure 4 As shown, the reference voltage circuit 22 includes an eleventh resistor R11 and a twelfth resistor R12.

[0050] One end of the eleventh resistor R11 can receive the external voltage VCC, the other end of the eleventh resistor R11 is electrically connected to one end of the twelfth resistor R12 and the comparison circuit 23 respectively, and the other end of the twelfth resistor R12 is grounded.

[0051] The eleventh resistor R11 and the twelfth resistor R12 can divide the external voltage VCC, and the divided voltage is the preset reference voltage.

[0052] The preset reference voltage can be expressed as Vref=VCC*R12 / (R11+R12). It can be seen that the preset reference voltage Vref is proportional to the external voltage VCC, Vref:VCC=R12:(R11+R12).

[0053] Therefore, by adjusting the resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12 , the proportional relationship between the preset reference voltage Vref and the external voltage VCC can be adjusted.

[0054] The comparison circuit 23 is electrically connected to the voltage sampling circuit 21 , the reference voltage circuit 22 and the driving circuit 40 respectively, and can output a zero-crossing detection signal to the driving circuit 40 in response to the sampling voltage output by the voltage sampling circuit 21 and the preset reference voltage output by the reference voltage circuit 22 .

[0055] The comparison circuit 23 can change its output state when the voltage between the preset reference voltage Vref and the sampling voltage Vs passes through zero. Since the sampling voltage Vs is usually superimposed with a fluctuating voltage, if the comparison circuit 23 does not adopt a hysteresis comparison function, it is easy to cause the output of the comparison circuit 23 to change continuously, resulting in output oscillation. In order to avoid the output oscillation, the comparison circuit 23 has a hysteresis voltage in a certain voltage range. The existence of the hysteresis voltage makes the detection points of the output change of the comparison circuit 23 become two, one is to detect the upper threshold voltage, and the other is to detect the lower threshold voltage. The voltage difference between the upper threshold voltage and the lower threshold voltage is the hysteresis voltage.

[0056] Since the comparison circuit 23 allows the preset reference voltage Vref to be compared with a voltage within a certain voltage range, it prevents the output signal from changing immediately when the sampled voltage Vs is slightly changed due to interference, thereby improving the circuit's anti-interference capability.

[0057] In some embodiments, Figure 4 As shown, the comparison circuit 23 includes an operational amplifier U1 , a first resistor R1 , a second resistor R2 , a third resistor R3 and a first diode D1 .

[0058] The anode of the first diode D1 and one end of the first resistor R1 are electrically connected to the voltage sampling circuit 21, the cathode of the first diode D1 can receive the external voltage VCC, the other end of the first resistor R1 is electrically connected to the inverting input terminal of the operational amplifier U1, one end of the second resistor R2 is electrically connected to the reference voltage circuit 22, the other end of the second resistor R2 is electrically connected to the non-inverting input terminal of the operational amplifier U1 and one end of the third resistor R3, and the other end of the third resistor R3 and the output terminal of the operational amplifier U1 are electrically connected to the driving circuit 40.

[0059] In this embodiment, the operational amplifier U1 is the core of the comparison circuit 23 and is used to compare the magnitudes of two input voltages.

[0060] The first resistor R1 and the second resistor R2 are input resistors of the operational amplifier U1 .

[0061] In operational amplifier U1, input resistance plays an important role. It connects and matches the signal source and the subsequent circuit, affecting the performance and stability of the entire circuit. The signal source may have different output impedances. If it does not match the input impedance of operational amplifier U1, the signal output by the signal source will be partially reflected back, thus affecting the operation of the entire circuit. The presence of input resistance allows the signal source to see a load that matches its output impedance and transmit the signal to the greatest extent. Reducing the reflected input resistance can also reduce the load impact on the signal source and achieve matching between the signal source and operational amplifier U1.

[0062] In practical applications, the current and voltage output by the signal source may be limited. If it is directly connected to the input of the operational amplifier, it will generate additional load on the signal source, thus affecting the output of the signal source. Through the appropriate input resistance, this load can be minimized, reducing the interference to the signal source. The input resistance can also achieve stable and accurate signal amplification.

[0063] The operational amplifier U1 is the core of the comparison circuit 23 , and the stability of its output signal is crucial to the performance of the entire circuit. The input resistor can provide a stable input voltage, thereby ensuring the stability of the output signal of the comparison circuit 23 .

[0064] The first diode D1 is used for the input voltage of the operational amplifier U1 to prevent the operational amplifier U1 from being damaged due to excessive input voltage.

[0065] The third resistor R3 is a positive feedback network introduced on the basis of the operational amplifier U1 as a comparator. Because of the positive feedback, the output of the operational amplifier U1 is saturated. According to the virtual circuit, the voltage of the non-inverting input terminal of the operational amplifier U1 Vo = (R2 + R12) * Vo / (R2 + R3 + R12), Vo is the output voltage of the operational amplifier U1.

[0066] See also Figure 3 In the process that the inverting input voltage Vi (i.e., the sampling voltage Vs) of the operational amplifier U1 gradually increases, when the inverting input voltage Vi of the operational amplifier U1 is greater than the non-inverting input voltage VT of the operational amplifier U1, the operational amplifier U1 outputs a negative saturation voltage -Vo. At this time, the non-inverting input voltage of the operational amplifier U1 changes from VT to -VT. Therefore, even if the inverting input voltage Vi of the operational amplifier U1 is less than the voltage VT, the operational amplifier U1 will not immediately output the positive saturation voltage Vo. Instead, the operational amplifier U1 will output the positive saturation voltage Vo only when the inverting input voltage Vi of the operational amplifier U1 is less than the voltage -VT.

[0067] Therefore, when the operational amplifier U1 outputs a positive saturation voltage Vo or a negative saturation voltage -Vo, the operational amplifier U1 will not change the output due to a slight voltage fluctuation of the sampling voltage Vs, thereby improving the anti-interference ability and stability of the circuit.

[0068] It can be understood that the voltage VT is the upper threshold voltage of the comparison circuit 23 , and the voltage −VT is the lower threshold voltage of the comparison circuit 23 .

[0069] In some embodiments, please refer to Figure 2 The driving circuit 40 includes a logic circuit 41 and a switch circuit 42 .

[0070] The logic circuit 41 is electrically connected to the controller 30 and the zero-crossing detection circuit 20, respectively. The logic circuit 41 includes a node 40a, and can output a driving signal in response to a control signal output by the controller 30 and a zero-crossing detection signal output by the zero-crossing detection circuit 20. The driving signal includes a first level type signal and a second level type signal, and the first level type signal and the second level type signal are different level type signals, for example, the first level type signal is a high level signal, and the second level type signal is a low level signal, or the first level type signal is a low level signal, and the second level type signal is a high level signal.

[0071] In some embodiments, please refer to Figure 4 , the logic circuit 41 includes a second diode D2 and a third diode D3.

[0072] The anode of the second diode D2 is electrically connected to the controller 30 , the cathode of the second diode D2 is electrically connected to the anode of the third diode D3 and the switch circuit 42 at a node 40 a , and the cathode of the third diode D3 is electrically connected to the zero-crossing detection circuit 20 .

[0073] In this embodiment, when the zero-crossing detection signal is a high-level signal, if the control signal is also a high-level signal, the voltage of the node 40a is a high-level signal, that is, the drive signal is a high-level signal; if the control signal is a low-level signal, the voltage of the node 40a is a low-level signal, that is, the drive signal is a low-level signal; when the zero-crossing detection signal is a low-level signal, regardless of whether the control signal is a high-level signal or a low-level signal, the voltage of the node 40a is a low-level signal, that is, the drive signal is a low-level signal.

[0074] The switch circuit 42 is electrically connected to the gate G of the thyristor 10 and is electrically connected to the logic circuit 41 at the node 40a. The switch circuit 42 can respond to the driving signal output by the logic circuit 41 to drive the thyristor 10 to conduct or disconnect the mains power supply circuit.

[0075] In some embodiments, please refer to Figure 4 The switch circuit 42 includes an NPN transistor Q1, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6.

[0076] One end of the fourth resistor R4 is electrically connected to the logic circuit 41 at the node 40a, the other end of the fourth resistor R4 is electrically connected to the base of the NPN transistor Q1 and one end of the fifth resistor R5, the emitter of the NPN transistor Q1 and the other end of the fifth resistor R5 are electrically connected to the gate G of the thyristor 10, the collector of the NPN transistor Q1 is electrically connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 can receive the external voltage VCC.

[0077] In this embodiment, when the driving signal at the node 40a is a high level signal, the NPN transistor Q1 is in the on state and the thyristor 10 is also in the on state. When the driving signal at the node 40a is a low level signal, the NPN transistor Q1 is in the off state and the thyristor 10 is also in the off state.

[0078] The fourth resistor R4 is used as a current limiting resistor to limit the base current flowing into the NPN transistor Q1 to prevent the base current flowing into the NPN transistor Q1 from being too large.

[0079] The fifth resistor R5 can make the base current of the NPN transistor Q1 change less when the input signal changes greatly, reduce the disturbance effect of the input signal, improve the anti-interference ability of the NPN transistor Q1, and ensure the stable operation of the NPN transistor Q1.

[0080] The sixth resistor R6 is used as a current limiting resistor to limit the current flowing into the gate G of the thyristor 10 to prevent the current flowing into the gate G of the thyristor 10 from being too large.

[0081] In some embodiments, please refer to Figure 2 The power supply circuit 100 further includes a bias circuit 50 .

[0082] The bias circuit 50 is electrically connected to the driving circuit 40 , the gate G of the thyristor 10 , and the second main electrode T2 of the thyristor 10 , respectively.

[0083] The bias circuit 50 is used to improve the anti-interference capability of the thyristor 10 .

[0084] In some embodiments, please refer to Figure 4 , the bias circuit 50 includes a thirteenth resistor R13.

[0085] One end of the thirteenth resistor R13 is electrically connected to the gate G of the thyristor 10 and the driving circuit 40 , respectively, and the other end of the thirteenth resistor R13 is electrically connected to the second main electrode T2 of the thyristor 10 .

[0086] In order to further explain the working principle of a power supply circuit provided by the embodiment of the utility model, Figure 4 To elaborate.

[0087] When it is necessary to control the thyristor 10 to conduct the mains power supply circuit, the controller 30 outputs a high-level signal. If the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 is less than the preset voltage threshold at this time, it means that the AC power is at a zero-crossing point. At this time, the sampling voltage Vs after the voltage is divided by the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is input to the inverting input terminal of the operational amplifier U1, so that the sampling voltage Vs is less than the non-inverting input terminal voltage of the operational amplifier U1, so the output terminal of the operational amplifier U1 outputs a high-level signal. The high-level signal cannot affect the signal of the node 40a due to the obstruction of the third diode D3. At the same time, the high-level signal output by the controller 30 is applied to the node 40a through the second diode D2. Since the signal at the node 40a is a high-level signal, the NPN transistor Q1 is in a conducting state, and the thyristor 10 is also The controller 30 is in the on state, thereby conducting the mains power supply circuit; if the voltage between the first main electrode T1 of the thyristor 10 and the second main electrode T2 of the thyristor 10 is greater than the preset voltage threshold at this time, it means that the alternating current is not at the zero point. At this time, the sampling voltage Vs after the voltage is divided by the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is input to the inverting input terminal of the operational amplifier U1, so that the sampling voltage Vs is greater than the voltage of the non-inverting input terminal of the operational amplifier U1, so the output terminal of the operational amplifier U1 outputs a low-level signal, and the low-level signal pulls down the voltage of the node 40a through the third diode D3. Therefore, even if the controller 30 outputs a high-level signal at this time, the signal of the node 40a is still a low-level signal. Since the signal of the node 40a is a low-level signal, the NPN transistor Q1 is in the off state, and the thyristor 10 is also in the off state, thereby disconnecting the mains power supply circuit. It can be understood that when the controller 30 continuously outputs a high-level signal, the mains power supply circuit will continuously switch between on and off as the voltage of the alternating current changes.

[0088] When it is necessary to control the thyristor 10 to disconnect the mains power supply circuit, the controller 30 outputs a low-level signal, which pulls down the voltage of the node 40a, regardless of whether the AC power is at a zero-crossing point at this time, that is, regardless of whether the output end of the operational amplifier U1 outputs a high-level signal or a low-level signal, the signal of the node 40a is still a low-level signal, so the NPN transistor Q1 is in the cut-off state, and the thyristor 10 is also in the cut-off state, thereby disconnecting the mains power supply circuit. It can be understood that when the controller 30 continues to output a low-level signal, the mains power supply circuit will always be in a disconnected state.

[0089] As another embodiment of the present invention, the present invention provides a circuit board, which includes the power supply circuit 100 as described above. The circuit board can be an independent circuit board or a circuit board formed by splicing multiple circuit boards.

[0090] As another embodiment of the present invention, the embodiment of the present invention further provides an electronic device, which includes the circuit board as described above.

[0091] Finally, it should be noted that the utility model can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of the utility model. The purpose of providing these implementation methods is to make the understanding of the disclosure of the utility model more thorough and comprehensive. In addition, under the idea of ​​the utility model, the above-mentioned technical features continue to be combined with each other, and there are many other changes in different aspects of the utility model as described above, which are all considered to be within the scope of the utility model specification; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the utility model.

Claims

1. A power supply circuit, It is characterized in that include: A thyristor, comprising a gate, a first main electrode and a second main electrode, wherein the first main electrode of the thyristor is used to electrically connect to a load, the load and the thyristor can form a mains power supply circuit, the thyristor can turn on or off the mains power supply circuit, and when the mains power supply circuit is formed, the load can be powered; a zero-crossing detection circuit, electrically connected to the first main electrode of the thyristor and the second main electrode of the thyristor, respectively, and configured to output a zero-crossing detection signal in response to a voltage between the first main electrode of the thyristor and the second main electrode of the thyristor; A controller, used for outputting a control signal; The driving circuit is electrically connected to the zero-crossing detection circuit, the controller and the gate of the thyristor respectively, and is used to respond to the zero-crossing detection signal output by the zero-crossing detection circuit and the control signal output by the controller to drive the thyristor to turn on or off the mains power supply circuit.

2. The power supply circuit according to claim 1, It is characterized in that The zero-crossing detection circuit comprises: A voltage sampling circuit, electrically connected to the first main electrode of the thyristor and the second main electrode of the thyristor, respectively, for sampling the voltage between the first main electrode of the thyristor and the second main electrode of the thyristor, and outputting a sampled voltage; A reference voltage circuit, used for generating a preset reference voltage; The comparison circuit is electrically connected to the voltage sampling circuit, the reference voltage circuit and the driving circuit respectively, and is used to respond to the sampling voltage output by the voltage sampling circuit and the preset reference voltage output by the reference voltage circuit, and output a zero-crossing detection signal to the driving circuit.

3. The power supply circuit according to claim 2, It is characterized in that The voltage sampling circuit comprises: A first voltage divider circuit is electrically connected to the first main electrode of the thyristor; The second voltage-dividing circuit is electrically connected to the first voltage-dividing circuit, the comparison circuit and the second main electrode of the thyristor respectively.

4. The power supply circuit according to claim 2, It is characterized in that The comparison circuit includes an operational amplifier, a first resistor, a second resistor, a third resistor and a first diode; The anode of the first diode and one end of the first resistor are electrically connected to the voltage sampling circuit, the cathode of the first diode is used to receive a preset voltage, the other end of the first resistor is electrically connected to the inverting input terminal of the operational amplifier, one end of the second resistor is electrically connected to the reference voltage circuit, the other end of the second resistor is electrically connected to the non-inverting input terminal of the operational amplifier and one end of the third resistor, and the other end of the third resistor and the output terminal of the operational amplifier are electrically connected to the driving circuit.

5. The power supply circuit according to claim 1, It is characterized in that The driving circuit comprises: A logic circuit, electrically connected to the controller and the zero-crossing detection circuit, respectively, the logic circuit comprising a node, for responding to a control signal output by the controller and a zero-crossing detection signal output by the zero-crossing detection circuit, and outputting a driving signal at the node; The switch circuit is electrically connected to the gate of the thyristor and to the logic circuit at the node, and is used to respond to the drive signal output by the logic circuit to drive the thyristor to turn on or off the mains power supply circuit.

6. The power supply circuit according to claim 5, It is characterized in that The logic circuit includes a second diode and a third diode; The anode of the second diode is electrically connected to the controller, the cathode of the second diode is electrically connected to the anode of the third diode and the switch circuit at the node, and the cathode of the third diode is electrically connected to the zero-crossing detection circuit.

7. The power supply circuit according to claim 5, It is characterized in that The switch circuit includes an NPN transistor, a fourth resistor, a fifth resistor and a sixth resistor; One end of the fourth resistor is electrically connected to the logic circuit at the node, the other end of the fourth resistor is electrically connected to the base of the NPN transistor and one end of the fifth resistor, the emitter of the NPN transistor and the other end of the fifth resistor are electrically connected to the gate of the thyristor, the collector of the NPN transistor is electrically connected to one end of the sixth resistor, and the other end of the sixth resistor is used to receive an external voltage.

8. The power supply circuit according to any one of claims 1 to 7, It is characterized in that Also included is a bias circuit; The bias circuit is electrically connected to the driving circuit, the gate of the thyristor and the second main electrode of the thyristor respectively.

9. A circuit board, It is characterized in that The invention comprises a power supply circuit as claimed in any one of claims 1 to 8.

10. An electronic device, It is characterized in that Comprising the electronic device as claimed in claim 9.

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